Summary: WE2B-5
Time Domain Characterizationof PowerAmplifiers with Memory Effects
P. Draxler*, I. Langmore, T.P. Hung, and P.M. Asbeck
University of Califomia, San Diego, La Jolla, CA 92093-0407
*QualcommInc., San Diego, CA 92121
Abstract - Memory effects in power amplifier
nonlinearity are frequently an impediment to amplifier
linearization. In this paper, memory effects in a cellular
phone power amplifier are characterized via time domain
measurements, with waveforms including steps, triangular
waveforms and CDMA signals. Memory effects found with
different waveforms are shown to be consistent, and in
agreement with measurements made with sinusoids in two-
tone tests. The results are analyzed by considering gain
modulation by a parameter varying at the baseband
frequency in response to the signal envelope. For
pseudorandom input signals, such as for CDMA, cross-
correlation of gain residues with the signal envelopeyields an
impulse response associated with the memory effects.
I. ~NTRODUCTION